Ruby開發的面向文檔的數據庫 RDDB

RDDB 是一個 Ruby 開發的面向文檔的數據庫系統，其靈感來自 CouchDB。它具有以下特性：

* Documents are simply collections of name/value pairs.
* Views can be defined with Ruby code, mapping from a document to any other data structure, such as a String, Array or Hash.
* A reduce block can be defined to reduce the initial mapped data from a view.
* Views can be materialized to improve query performance.
* Datastores are pluggable. Current implementations are RAM, partitioned files and Amazon S3.
* Viewstores are pluggable. Current implementations are RAM, file system and Amazon S3.
* Materialization stores are pluggable. Current implementations are RAM, file system and Amazon S3.
* Distributed materialization may work, but it's going to be rewritten.

示例代碼：

  # First create an database object
  database = Rddb::Database.new

  # Put some documents into it
  database << {:name => 'John', :income => 35000}
  database << {:name => 'Bob', :income => 40000}
  database << {:name => 'Jim', :income => 37000}

  # Create a view that will return the names
  database.create_view('names') do |document, args|
    document.name
  end

  # The result of querying will return an array of names
  assert_equal ['John','Bob','Jim'], database.query('names')

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